Vertical power semiconductor devices that control a load current flow between a first load electrode at a front side and a second load electrode at a rear side of a semiconductor die typically include doped regions that are formed in semiconductor layers, e.g., drift zones, compensation structures, buffer layers and/or field stop layers.
Properties of vertical dopant profiles of such doped regions, for example, steepness, uniformity, smoothness and undulation may have substantial impact on device parameters. Typically, a vertical dopant profile in an epitaxial layer is shaped by controlling a doping gas supply with time or by ion implantation followed by a heat treatment for diffusing the implanted dopants.
There is a need for an improved doping method and for semiconductor devices with improved dopant profiles.